Red Bull certainly found more between Friday and Saturday then Merc did. I'm wondering if Hamilton ran with his engine in a slightly reduced performance mode and whether he's going to be compromised on the engine side of things for the remainder of the season. Wolff has admitted they've got a reliability niggle that's emerged and on the engine supply front they're under a lot of pressure (3x new Merc engine for Austin, Merc-related grid penalties are starting to stack up now).
If Merc have decided they want to avoid any more grid penalties for Hamilton, they might be running his engine slightly conservative to prevent the niggle developing.
The Mercedes looked great on Friday but the unusually high track temperature on Saturday & Sunday saw the Red Bull being much the fastest car. This meant that the race was Verstappen’s to lose which he almost did with a terrible start that would have seen him down to third of Bottas was about.
The issue for Hamilton for the rest of the season is now hot tracks as the Mercedes clearly does not like them. The hotter the better for the Red Bull though.